RANDOM_OBJ = {
  alphabet: ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"],
  fourdirs: ["东","西","南","北"],
  allcards: ['A', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K'],
  pick: function (ar, num) {
	var res=new Array;
	var len=ar.length;
	for(var i = 0; i<num; i++){
		var j = RANDOM.integer(0, len-1);
		res[i] = ar[j];
	}
	return res;
  },
  letter: function (num){
	return(RANDOM_OBJ.pick(RANDOM_OBJ.alphabet, num).join(' '));
  },
  direction: function (num){
	return(RANDOM_OBJ.pick(RANDOM_OBJ.fourdirs, num).join(' '));
  },
  cards: function(num) {
	return(RANDOM_OBJ.pick(RANDOM_OBJ.allcards, num).join(' '));
  }
};
